The US has played an active role in Iran's domestic politics since it covertly supported a coup which removed Mohammad Mossadeq, the architect of Iran's energy nationalisation drive, from power in 1951.
|Iran and the US have been in a state of hostility since 1979 [GALLO/GETTY]
By re-instituting the Shah in Iran, Washington began to alienate an increasingly influential cleric class which 28 years later would help remove the monarchy in the Islamic revolution.
The US severed its diplomatic relations with Iran following the seizure of American hostages in Tehran in 1979.
Here is a review of key dates which shaped Iran's relations with the US.
1951: Mohammad Mossadeq, a nationalist, is elected by the lower house of the Iranian Legislature to be prime minister. In a move that would anger the West and set the tone for decades to come, Mossadeq decrees the nationalisation of the oil industry just days after he is appointed.
July 17, 1952: The Shah's refusal to allow Mossadeq to appoint some of his own cabinet leads the prime minister to resign. Five days of rioting ensues after which the Shah, under pressure, reinstates Mossadeq and concedes to his demands. For the next year, Mossadeq passes reforms limiting the Shah's unconstitutional powers.
August 19, 1953: Mossadeq is deposed by his military officers in a coup orchestrated by American and British intelligence agencies, restoring power to the Shah.
February 24, 1955: Iran joins the US-backed Baghdad Pact, known as the Central Treaty Organisation (Cento), modelled after Nato and designed to contain Soviet expansion.
1964: Ayatollah Ruhollah Khomeini, a religious leader and fierce critic of the Shah, begins what would be 14 years of exile in Iraq.
January 16, 1979: The US-backed Shah is forced to flee to Egypt.
February 1, 1979: Khomeini returns from exile and seizes power.
|Crowds greeted Khomeini upon his return[GALLO/GETTY]
The new Iranian government terminates its membership in the Baghdad Pact.
November 4, 1979: Iranian students seize 63 hostages at the American embassy in Tehran demanding the return of the Shah to face trial.
The US severs diplomatic ties and imposes sanctions on Iran.
September 22, 1980: In a war that would last for the next eight years, Western-backed Iraq invades Iran.
January 20, 1981: The last 52 hostages are freed a few hours after Jimmy Carter, the then US president, leaves office. They were held for 444 days.
1985-6: In exchange for Iranian assistance in freeing US hostages kidnapped by Hezbollah, American weapons are sold via Israel to Iran. These illegal funds are used to help Nicaraguan rebels. This comes to be known as the Iran-Contra scandal.
July 3, 1988: Iran Air Flight 655 is shot down by the USS Vincennes in the Gulf, killing all 290 people on board. This follows an incident a month earlier when the same cruiser opened fire on Iranian small boats searching a bulk carrier.
August 2, 1990: Iraq invades Kuwait.
January 1991: Iran remains neutral during the Gulf War.
1995: Oil and trade sanctions are imposed on Iran by Bill Clinton, the then US president, after he accuses Tehran of sponsoring terrorism and seeking to acquire weapons of mass destruction.
1996: Clinton increases sanctions on Iran and penalises any firm investing $40 million or more a year in Iran.
1997: Mohammed Khatami is elected president of Iran. He calls for dialogue with the American people in an interview on US network television.
February 18, 2000: Clinton extends sanctions on US oil contracts with Iran after Iranian reformists win in the general election.
September 2000: Madeleine Albright, the then US secretary of state, meets with Kamal Kharrazi, the then Iranian foreign minister, at the UN for the first such talks since the Iranian revolution in 1979.
June 2001: The US accuses Iran of being directly involved in the bombing of an American military base in Saudi Arabia, evoking an angry rejection of the charges by Tehran.
September 2001: A report by the CIA accuses Iran of having one of the most active nuclear weapons programmes in the world and of seeking missile-related technology from countries including China and Russia.
January 29, 2002: George Bush, the then US president, dubs Iran, Iraq and North Korea an "axis of evil" in his State of the Union address.
|Bush said Iran was part of an axis of evil [AFP]
September 2002: Iran's first nuclear reactor at Bushehr begins construction with the help of Russian technicians, prompting strong objections from the US.
December 2002: The US accuses Iran of a clandestine nuclear weapons programme with two nuclear sites under construction at Natanz and Arak.
February-May, 2003: The International Atomic Energy Agency (IAEA) concludes that the nuclear sites at Natanz and Arak are indeed under construction but designed solely to provide fuel for future power plants.
October-November, 2003: Iran agrees to tougher UN inspections of its nuclear facilities and to suspend its uranium enrichment. The IAEA reports that Iran admitted to producing plutonium but cites no evidence of trying to build a nuclear bomb.
December 2003: After earthquakes kill up to 50,000 people in the Iranian city of Bam the US sends humanitarian aid to help.
November 2004: Iran agrees to a European offer stipulating that Iran suspend its uranium enrichment in exchange for trade concessions.
January 2005: Europe and Iran begin trade talks; the EU (France, Germany and the UK) demand Iran stops its uranium enrichment permanently.
March 2005: Bush backpedals from his usual hard-line stance and says the US will back the EU negotiating track, offering economic incentives in exchange for Iran abandoning its nuclear aspirations. Bush also announces the lifting of a decade-long block on Iranian membership of the World Trade Organisation.
July 2005: The US says that Mahmoud Ahmadinejad, the newly-elected Iranian president, was a leader behind the hostage crisis in 1979 but is uncertain of his role in taking the American prisoners.
August 2005: Bush makes one of many statements to follow about not ruling out the use of force against Iran.
April: Washington denies a claim reported in The New Yorker suggesting that the US may be planning a tactical nuclear strike against Iranian underground nuclear sites.
Iran complains to the UN and says it will retaliate against any attack. Ahmadinejad reiterates Iran's peaceful pursuit of nuclear technology. Iran offers to hold direct talks with the US on Iraq but later withdraws its offer.
May: Iran's parliament threatens to withdraw from the Non-Proliferation Treaty if pressure over its nuclear programme escalates following a draft resolution at the UN Security Council.
The US, later that month, offers to join EU nations in direct talks if Iran agrees to suspend uranium enrichment.
December: A resolution is passed by the Security Council imposing sanctions on Iran due to its nuclear programme.
January: Members of the Iranian Revolutionary Guard are allegedly arrested in Iraq by US forces for engaging in sectarian warfare. A few days after lumping Iran in with al-Qaeda in his State of the Union address, Bush clarifies that he does not intend to attack Iran.
May: Ryan Crocker, the US ambassador to Iraq, and Hassan Kazemi Qomi, the Iranian ambassador to Iraq, hold talks on Iraq's security.
August: Reported US plans to designate Iran's Revolutionary Guards (IRGC) as foreign terrorists is denounced as "worthless" by Iranian officials. Bush warns Iran against supporting militias fighting against American forces in Iraq.
September: Ahmedinejad is denied a request to visit the site of the September 11 attacks. Ahmedinejad also says that Iran is not pushing for a military conflict with the US.
October: Hassan Kazemi Qomi is accused by US military commander General David Petraeus of belonging to the elite unit of Iran's Revolutionary Guards, the Quds Force.
November: Twenty Iranian citizens are released by US forces in Iraq.
The IAEA issues a new report saying that Iran supplied transparent data on its past nuclear activities but still has limited knowledge of current Iranian nuclear activities.
December: A US intelligence report says that Iran halted its nuclear weapons programme earlier in 2003: but was still continuing uranium enrichment.
|The IAEA has been seeking more inspections of Iran's nuclear facilities [EPA]
Ahmadinejad hails the US report as an Iranian victory, but Bush says Iran risks further international isolation if it does not reveal the full extent of its nuclear activities.
Robert Gates, the US defence secretary, tells a Bahrain conference that Iran may have restarted its nuclear weapons programme despite the US intelligence report, and says that Iran still poses a serious threat to the Middle East and the US.
Iran protests in a formal letter to the US about alleged spying on its nuclear activities.
January: Khamanei, the Supreme Leader of Iran, says relations could be restored with the US in the future. The US accuses Iran of harassing US Navy ships in the Strait of Hormuz.
Bush accuses Iran of being the world's leading sponsor of terrorism.
July: The US plans to establish the first diplomatic presence in Iran in around 30 years by opening an interests section in Tehran.
September: Barack Obama, the US Democratic presidential candidate, offers Iran talks without preconditions.
November: Obama is elected president and is congratulated by Ahmadinejad.
January 28: The Obama administration continues to signal that they are ready for direct talks with Iran, but promises further pressure if they do not halt their nuclear activity. Ahmadinejad says that the US must make sweeping changes to its foreign policy.
January 29: A White House spokesman refuses to rule out the use of force in dealing with Iran, saying Obama will still "preserve all his options".
February 3: Iran announces the launch of its first domestically-produced satellite, Omid (hope), raising fears in the West that it could give Iran the capacity to launch intercontinental ballistic missiles.
February 4: Officials from the US, Russia, Britain, France, Germany and China meet in Frankfurt to discuss Iran's nuclear programme.
March 20: Obama issued a videotaped appeal to Iran offering a "new beginning" in US-Iranian relations.
June 2009: Iran witnesses the largest street demonstrations since the revolution in 1979 as hundreds of thousands take to the streets to protest presidential election results that reelected Ahmadinejad by a landslide.
President Obama condemns the Iranian government's crackdown on protesters as "unjust"